The WL barrier has a weighted ballast bag that is sewn directly onto the front bib. This ballast bag creates a uniform weight across the length of the dam and molds to the shape of the terrain to limit seepage.
The seepage feature depends on two factors:
- The soil condition (the smoother the soil the better the watertighness)
- The draining effect (important for the long-term floods).
Watertightness increases with the flood height and the pressure exerted by the liquid on the floor fabric. The leakage rate is less than 1.06 Gallon (U.S) per min. and per linear meter on the smooth floor (concrete type). If this leakage rate is considered to be too great, it is possible to reduce it considerably by spreading under the leading edge a seal of mastic or silicone cartridge type, or natural products of molasses type